Integrated circuits such as microprocessors, memory elements, counters, serial adder/subtractors, and the like are typically comprised of subcircuits or functional blocks that communicate with each other through electrical interconnects. For example, the functional blocks of a microprocessor may include a microprocessor core, an integer arithmetic logic unit, an execution core, registers, cache, a floating point unit, an instruction decode and prefetch unit, a branch predictor, a bus interface, and the like. The functional blocks of a memory element, on the other hand, may include charge storage devices, sequential logic circuitry, and combinatorial logic circuitry. The functional blocks in turn comprise active and passive circuit elements such as transistors, capacitors, resistors, and inductors.
In operation, a power or a bias signal is supplied to the integrated circuit before it can receive, process, and transmit electrical signals. The power or bias signal is transmitted to the transistors of each functional block whether the functional blocks are in an active mode of operation or a standby mode of operation. Thus, the circuit elements, e.g., the transistors, receive power whether they are in active operation or not. A drawback of this type of configuration is that all the transistors in the circuit receive operating power, whether or not they are processing electrical signals. Because transistors that are receiving operating power leak current, they consume power. In portable applications such as laptop computers and cellular phones in which power is supplied by batteries, this power consumption limits the amount of time the portable device may be used before it should be recharged or the batteries replaced.
Accordingly, it would be advantageous to have an integrated circuit capable of operating at a reduced power consumption and a method for reducing power consumption of the integrated circuit. It would be of further advantage for the method and structure to be cost efficient.